I just wanted to throw this out there because I sometimes use something while it's charging the secret has to do with using a smart charger. You can make your own charging circuits as well that regulates the current allowed to be drawn and can adjust that based on the draw of item using power. I know most people won't do this but you definitely can.

I'm late to the post on this but yes I agree - As long as the equipment using power uses less than the charger is supplying the batteries will charge. If you are doing this on purpose like for example a charging dock then make sure your charger can support both the current from your equipment and also meet the recommended charging requirements of your batteries.

yea that's why I was asking Josh.